As positive photoresist composition there are normally used compositions comprising an alkali-soluble resin and a diazonaphthoquinone compound as a photosensitive material. Example of such composition include novolak type phenol resins, diazonaphthoquinone substituted compounds as disclosed in U.S. Pat. No. 4,173,470. Most typical examples of such composition include novolak resin composed of cresol-formaldehyde/trihydroxybenzophenonediazonaphthoquinonesulfonic ester as disclosed in L. F. Thompson, introduction to microlithography, ACS publishing Co., No. 219, pages 112 to 121.
It is known to the skilled artisan to produce positive photoresist compositions, such as those described in patent U.S. pat. No. L. A. Colom et al. U.S. Pat. No. 3,666,473 used the resin and photo activating compounds are 1:0.25, here photo activating compound is used is excess. Some of the US patents are Buhr et al. U.S. Pat. No. 5,563,018, McKean et al. U.S. Pat. Nos. 5,580,602 and 5,702,756, Clecak et al. U.S. Pat. No. 4,397,937, Sezi et al. U.S. Pat. Nos. 5,863,705 and 6,110,637, Patrascu et al. U.S. Pat. No. 5,512,700, Oberlander U.S. Pat. No. 6,077,942, Sinta et al. U.S. Pat. No. 5,917,024, Canize et al. U.S. Pat. No. 5,612,164. These include water insoluble, aqueous alkali-soluble phenol-formaldehyde novolak resin together with light sensitive materials, usually a substituted diazonaphthoquinone compounds. The resins and photosensitizers are dissolved in an organic solvent or mixture of solvents and are applied as a thin film or coating to a substrate suitable for the particular application desired.